The present invention relates to an apparatus for inflating an inflatable vehicle occupant protection device and, more particularly, to a gas generating composition for a vehicle occupant protection apparatus.
An inflatable vehicle occupant protection device, such as an air bag, is deployed upon the occurrence of a vehicle crash. The air bag is part of a vehicle occupant protection apparatus, which further includes a crash sensor and an inflator. The inflator includes a housing, a gas generating material in the housing, and an igniter. The igniter is actuated so as to ignite the gas generating material when the vehicle experiences a collision for which inflation of the air bag is desired to protect the vehicle occupant. As the body of gas generating material burns, it generates a volume of inflation gas. The inflation gas is directed into the air bag to inflate the air bag. When the air bag is inflated, it expands into the vehicle occupant compartment and helps to protect the vehicle occupant.
Inflator housings may be formed from lightweight materials, such as aluminum. These lightweight materials can lose strength at abnormally high temperatures, such as those reached in a vehicle fire. At temperatures experienced in a vehicle fire, the gas generating material may autoignite and produce inflation fluid at a pressure sufficient to cause the inflator housing to lose its structural integrity due to the reduced strength of the inflator housing material. To prevent such loss of structural integrity, inflators typically include an autoignition material that will autoignite and initiate combustion of the gas generating material at a temperature below that at which the material of the housing begins to lose a significant percentage of its strength.
The present invention is an apparatus that comprises a vehicle occupant protection device and an actuator for the vehicle occupant protection device. The actuator includes a gas generating material or both a gas generating material and an autoignition material. Either the gas generating material or the autoignition material, or both the gas generating material and the autoignition material comprise a plasticized cyclodextrin nitrate ester. The plasticized cyclodextrin nitrate ester has an autoignition temperature in the range of about 150xc2x0 C. to about 180xc2x0 C. and is resistant to thermal decomposition at a temperature less than 150xc2x0 C.